Compositions and methods for planarizing or polishing the surface of a substrate are well known in the art. Chemical-mechanical planarization, or chemical-mechanical polishing (CMP), is a common technique used to planarize substrates. CMP utilizes a chemical composition, known as a CMP composition or more simply as a polishing composition (also referred to as a polishing slurry) for removal of material from the substrate. Polishing compositions typically are applied to a substrate by contacting the surface of the surface with a polishing pad (e.g., polishing cloth, or polishing disk) saturated with the polishing composition. The polishing of the substrate typically is further aided by the chemical activity of the polishing composition and/or the mechanical activity of an abrasive suspended in the polishing composition or incorporated into the polishing pad (e.g., fixed abrasive polishing pad).
Conventional CMP compositions and methods typically are not entirely satisfactory at planarizing substrates. In particular, CMP polishing compositions and methods can result in less than desirable polishing rates and high surface defectivity when applied to a substrate. Because the performance of many substrates is directly associated with the planarity of their surfaces, it is crucial to use a CMP composition and method that results in a high polishing efficiency, selectivity, uniformity, and removal rate and leaves a high quality polish with minimal surface defects.
CMP compositions often contain oxidizing agents, which can react with the surface of the substrate, particularly a metal-containing substrate, and render the surface more susceptible to removal by mechanical abrasion. Oxidizing agents containing iodine (e.g., iodine, iodides, iodates, and periodates) are particularly useful in polishing metal-containing substrates; however, iodine is not very soluble in typical CMP compositions.
There have been attempts to improve the solubility of iodine while maintaining its beneficial characteristics as an oxidizing agent in CMP. For example, soluble iodine can be created by combining elemental iodine with compounds such as iodide, polyvinylpyrrolidone, and starch. Although these compounds can be used in CMP compositions, these compounds have drawbacks. The tri-iodide complex that is formed by the combination of iodine and iodide requires an excess of iodide and causes significant staining of the material it contacts. Polyvinylpyrrolidone and starch are large molecules and often have an undesirable impact the polishing rate of the materials being polished. Thus, there remains a need for alternative polishing compositions and methods.